Fuel pump



FUEL PUMP Filed Dec. 30, 1931 3 Sheets-Sheet l W. G. NOACK FUEL PUMP 3 sheets-sheet 3 Filed Deo. 50, 1951 www IN1/EN To@ By my Patented @cto 6, i936 ll'lilll. il YU" Walter Gustav Noaclr, Baden, Switzerland, as-

signor to Holzwarth Gas Turbine Co.,

San

Francisco, Calif., a corporation lof Delaware Application December 30, 193i., Serial No. 583,911.1 )In Germany `anuary 3, 193i ll'l @Halma (Cl. 1103-50) My invention relates to fuel pumps and particularly to pumps suitable for use in connection with constant volume explosion chambers associated with explosion gas turbines or with steam generators.

It is already known to control the'valves of explosion engines bymeans of a pressure medium, such as pressure oil, instead of by cams and lever mechanism, such pressure medium being made to act upon pistons associated with the movable parts of the valves, the control of the pressure medium, which is delivered by a special pump, being effected through valves or rotary distributors. It has also been already proposed to employ pressure oil for operating fuel pumps. The operating conditions in the case of fuel pumps are, however, somewhat diiferent than in valves, as in fuel pumps comparatively large forces must be applied in very short times in order to secure rapid and powerful injections which last, however, for only a short period. .In the case of explosion turbines or of steam generators wherein the heating medium comprises gases produced by explosion, not only high injection pressures but also comparatively large quantities of fuel are necessary. The power that must be temporarily applied is therefore considerable, so that the power transmitting medium, such as controlled pressure oil, must either have very high pressure or be used in very large quantities or both. It is, however, very dimcult to fulll both these requirements, both from the structural and operating standpoints, by oil control, as the necessary sensitivity (prompt responsiveness and precision) cannot be obtained with devices which must involve large masses and resist high pressures.

In order to retain the advantages of the drive and control by pressure fluid, and at the same time avoid the disadvantages thereof for the special operating conditions associated with fuel pumps, it is proposed according to the present invention to separate the drive from the control of the pump by actuating the fuel-injecting pump piston by means of a separate 4operating oil and to effect the control or regulation of the fuel quantities fed by the pump by means of control oil which is regulated in any suitable manner. The operating oil can then be of any desired pressure and be employed in any desired quantity, while the control oil, which serves only to regulate the rate of fuel feed, can be employed in such quantity and at such pressure as will insure reliable and accurate regulation.

In the accompanying drawings forming part of vthis specification, is shown by way of example a preferred arrangement embodying the present invention, Fig. 1 being a diagrammatic View in section of the fuel pump and its operating and regulating mechanism, Fig. 2 a horizontal section through the distributor, and Fig. 3 an enlarged sectional View of the fuel pump. Figs. 4 and 5 show the condition of the oil feed regulating piston at different instants during the initia tion of a control movement in the upward and downward directions, respectively; while Fig. 6 illustrates the uppermost position of the piston.

The numeral I indicates the fuel pump, 2 the controller, in the form of a rotary distributor, for the control oil for the pump, 3 the pump for the control oil, which may for example oe mounted upon the same shaft as the governor l. The lat ter is driven by the engine which receives fuel from the pump. The oil pump for the operating oil is shown at 5. This pump is driven by a separate motor t which is coupled with the control device 2 through a reduction gearing shown conventionally at l. The actuation of the fuel pump I is accomplished by causing control oil fed by the pump 3 to pass through ports or slots 8 in the rotary member of the distributor 2 into the arcuate space defined by the blocks 9 (Fig. 2) and thence to the upper side of the control piston I i through the conduit Iil.- As will be seen from Fig. 3, the control piston i i has a larger diameter at its upper part lia than at its lower part IIb. The operating oil under pressure introduced by the conduit Ilia leading from the pump I5 thus exerts a greater force upon the horizontal surface of the part IIa than upon the horizontal surface of the part I Ib, so that there is always a differential force tending to move the piston upwardly. If the conduit I0 is not under pressure, the piston II will be moved upwardly until its topmost portion llc engages the stop I2a. In this position, the port I2b is closed. If,-however, as above-described, regulating oil is chargedv into the conduit iIl by the distributor 2, the total -downwardly acting pressure exerted by such regupartof larger diameter I3b. The pressure oil from the conduit Illa always has access through the port or ports I2c to the space I2d between the parts I3a and I3b. This pressure oil, due to the larger horizontal surface presented by the part I3b than by the part I3a, exerts a downwardly acting force upon the piston I3 (when no pressure oil enters through channel I2 into the space below the piston), the piston thus being constantly subjected to a force tending to lower the same. The piston I3 thus tends to move toward its lowest position wherein a shoulder on such piston engages the stop surface I3c. When, however, pressure oil enters through the channel I2 into the space below the piston I3, the total upward pressure exerted by such oil exceeds the downwardly directed differential pressure exerted by the oil from channel I 2c. The piston is thus rapidly raised and forces the liquid fuel located in space I4 through the bore provided withthe check valve I5 to the place of injection into the combustion chamber. In the meantime the blocks 9, which rotate with the rotary member 2, have brought the space I6, which is connected with an exhaust space, into communication with the conduit I0, so 4that the pressure' upon the piston II is relieved, the oil flowing off through conduit I1 and the piston II being forced up by the action ofthe operating oil which occupies the space I8 and bears preponderatlngly against the upper part IIa of the piston. By the movement of the piston I I upwardly until the surface I Ic strikes the stop I2a, the ports I 2b in the lower part IIb of the control piston II are closed and the ports I2e in said part IIb are brought into communication with the channel I2. The underside of the piston I3 is now connected with the discharge pipe I9 for operating oil and such piston now moves downwardly in order to suck in a new charge of fuel through the one way valve 20 from `a source of supply. This downward movement of the piston is effected, as above described, by the dierentlal pressure of the pressure oil charged by the conduit Illa into the space I2d. It will be seen from the above that the vpiston II operates in the manner of a slide valve to control the flow of operating oil for effecting movement of the fuel feeding piston in one or the other direction.

As can be seen from the drawings, the control member 2 is provided with further connections 2I and 22 which may serve for actuating the valves of the explosion chamber, e. g. the air inlet and the exhaust valve, as disclosed, for example, in .the patents to Hans Holzwarth No. 877,194, dated Jan. 2l, 1908 and No. 1,763,154, dated June l0, 1930. A second fuel pump, for a second explosion chamber, may be controlled through the opening 23 which is at the same level as the port 8. Above the housing of the distributor 2 is arranged an air chamber 24 which maintains the'control oil pressure at a substantially uniformvalue even with varying withdrawal of pressure oil. A small relief valve 25 may be provided to limit the pressure of the control oil.

The control oil serving for thecontrol of the operation of the fuel pump piston may also be employed satisfactorily for the regulation of the quantityof fuel itself by causing the speed governor to control the height of the control oil pressure. To this end the governor 4 is arranged to operate a slide valve 21a moving in a sleeve 21 having a port 26 leading'from an oil-filled annular space 26a into the interior of the sleeve. By means of the slide valve more or less leak flow area for oil is exposed depending upon the position of the governor collar 28, the oil escaping through-port 26 flowing into the exhaust conduit I1. Depending upon the magnitude of the area so exposed, the pressure of the control oil discharged into the conduit 30a by pump 3 is changed,'the same being already reduced by the throttling device 23. The oil pressure controlled from the governor position opera es upon a control piston 30 which is held in equilibrium by the spring 3|. If the oil pressure falls because a larger area in the sleeve 21 is exposed, dueto increase in the speed of the governor or to decrease in the load on the engine, the piston 30 rises under the influence of the spring, permits operating oil to pass beneath the piston 33 through the channels 32, as described more in detail below, and connects the space 34 over the piston 33 with the outer space of exhaust or atmospheric pressure through the openings 35, 35a and 35h. The piston 33 now rises until the flow of oil under the piston and the escape over the piston are checked. The piston 33 is now held in its position and with it the fulcrum 36 of the lever 31 which is moved from the fuel pump system through the follower 38 is maintained in fixed position. An overflow valve 39 is actuated in known manner by the lever 31, such valve permitting a part of the suckedin fuel quantity to ow back again out of space I4 into the suction conduit. Upon rise of the fulcrum 36, which occurs upon increase in speed of the governor, the opening of the overow valve occurs earlier, so that less fuel is supplied. When the fulcrum 36 falls, that is, when the control oil pressure is reduced as the speed of the governor decreases, the overflow valve opens to only a slight extent or not at all, so that all or nearly all of the sucked-in fuel is forced out by the pump and fed to the explosion chamber.

The relative movements of the pistons 30 and 33 will be clear from the following description and from Figs. 4, 5 and 6.

Fig. 4 shows the piston 33 in an intermediate position. A fall in the pressure of the oil in conduit 30a has caused the spring 3l to move the piston 36 upwardly `for a certain distance. In this way, there is initiated for the piston 33 an ex- I actly similar movement in the following manner: The upper control edge of the groove 32a. on the piston 30 opens the path of iiow through the bores 32 toward the lower side of the piston 33. Pressure oil from pipe I0a (see also Fig. l) can now enter through the bores 32 and occupy the space below the piston 33.. Simultaneously the upper control edge of the groove 35e on the piston 30 opens the path for the oil trapped above the piston 33 to the bore 35a through the upper bores 35. The trapped oil can now flow off through the bores 35, 35a and 35d. As pressureoil can thus flow under the piston 33 and as the oil aboveA the piston can flow olf, the piston 33 moves upwardly. By this upward movement the piston 33, however, itself again closes the path established by the upper control edges of the grooves 32a and 35e for the oil and must accordingly come to rest at the moment when the said upper control edges are again covered by the inner wall of the hollow piston 33. The relative position of the piston 33 and piston 30 which is then reached is shown clearly in Fig. 6, wherein the space below the piston 33, as well as the space above the piston, is completely closed, so that any movement of the piston 33 is made impossible. In this figure, the pistons 30 and 33 are in their uppermost positions. v

aosaaoe In similar fashion, the piston 33 follows the piston 30 downwardly when, as indicated in Fig. 5, an impulse is exerted through the conduit 30a upon the piston 30 against the pressure of spring 3l and moves the piston 30 a definite distance downwardly. By such downward movement of piston30 there is effected a similar movement of piston 33 and for the same distance. It being borne in mind that the piston 3 in Fig. 5 begins moving down from a position relatively to piston 33 which is similar to that shown in Fig. 6, it will be seen that the lower control edge of the groove 33a, creates a connection between the upper bores 32 and the bore 35h of piston 33, so that now the pressure oil entering through the bore 32 can flow through the groove 33a and the bore 35h to the upper side of such piston. Simultaneously, the lower control edge 33h opens a discharge path for the oil trapped below the piston 33 through the boresv 33e, 35a and 350Z. The piston 33 accordingly moves down under the influence of the oil pressure upon its upper surface, and for so long a distance until the lower control edges of the grooves 33a and til are again covered by the inner wall of piston 33, that is, until the relative position of the piston 33 and piston 30 is the same as illustrated in Figs. 3 and 6. When it reaches such position, the piston 33 remains stationary.

By separation of the control oil from the operating 'oil it becomes possible to combine the control of the pump and the regulation of the fuel quantities with comparatively small quantities of oil and with low oil pressure, and to operate with greater precision. The use of a separate operating oil makes it also possible to apply great power for the drive of the pump, particularly when an air chamber is associated likewise with the feed conduit for the operating oil, such air chamber rendering available momentarily rather large quantities of oil without considerable fall in pressure. It will be understood that the various conduits and oil spaces do not become alternately filled with and emptied of oil; there is preferably always a body of oil in such spaces which alternately is relieved of pressure and ,transmits pressure impulses, so that the movement of large bodies of oil is avoided.

I claim:

1. A fuel pump system suitable for explosion chambers, comprising a cylinder, a piston re` voperated by a separate body of control oil of rela.-

tively low pressure for controlling the ow of said operating oil, and means for charging such control oil to said mechanism.

2. A fuel pump system as set forth in claim ll, including mechanism for regulating the quantity of oil charged by the pump, means for charging to said mechanism the same control oil which controls said motor piston, and a common source of o il for said mechanism and said motor piston.

3. A fuel pump system as set forth in claim l, including a rotary timing device in the circuit of the control oil for timing the flow of control oil to said hydraulic mechanism.

4. A fuel pump system as set forth in claim 1, including a timing device for the low pressure control oil arranged at a distance from the fuel pump, said hydraulic mechanism being located near said pump, and a conduit connecting said timing device and said mechanism.

5. A fuel pump system suitable for explosion chambers, comprising a cylinder, a fuel feeding piston reciprocable therein, a fuel feed conduit and a fuel discharge conduit connected with the cylinder space at one end of the piston, hydraulic mechanism for operating said piston comprising a source of liquid under pressure, a slide valve controlling the flow of such pressure liquid to said piston to regulate the reciprocating movement thereof, a fluid conduit associated with the slide valve and adapted to charge a liquid under pressure thereto to actuate the same, and a timing mechanism interposed in said last-mentioned conduit for periodically regulating the pressure therein to time the actuation of the slide valve and thereby of the fuel feeding piston.

6. A fuel pump system suitable for explosion chambers, comprising a cylinder, a fuel feeding piston reciprocable therein, a fuel feed conduit and a fuel discharge conduit connected with the cylinder space at one end of the piston, a motor cylinder and piston for operating the fuel feeding piston, a pressure fluid conduit, a slide valve associated with said conduit for directing fluid under pressure from said conduit to one or the other side of the motor piston, and hydraulic mechanism for operating the slide valve and comprising a conduit, a source of pressure fluid, and a timing device interposed in said last-mentioned conduit between the source of pressure uid and the slide valve to time the operation of the slide valve and thereby of the fuel feeding piston.

7. A fuel pump system suitable for explosionchambers, comprising a cylinder, a fuel feeding piston reciprocable therein, a fuel feed conduit vand a fuel discharge conduit connected with the nism, and means for varying the pressure in said last-mentioned conduit.

8. A fuel pump system suitable for explosion chambers, comprising a cylinder, a fuel feeding piston reciprocable therein, a fuel feed conduit and a fuel discharge conduit connected with the cylinder space at one end of the piston, means for operating the piston, a valve associated with said cylinder space for by-passing a portion of the fuel sucked into `the cylinder, means movable with the piston for operating the by-pass valve, hydraulically operated mechanism connected with said means for determining the position thereof relatively to the by-pass valve and thereby determining the effective fuel feeding stroke of the piston, a pressure fluid conduit connected with said mechanism, and means for regulating the pressure in said last-mentioned conduit and thereby predetermining the position of said valve operating means with respect to said valve.

9. A fuel pump system suitable for explosion chambers, comprising a cylinder, a fuel feeding piston reciprocable therein and having a fixed stroke, a fuel feed conduit and a fuel discharge conduit connected with the cylinder space at one end of the piston, means for operating the piston, a valve associated with said cylinder space for by-passing a portion of the fuel sucked into the cylinder, hydraulically operated mechanism associated with the by-pass valve and operating to determine the instant of opening of the valve with relation to the beginning oi' the feed stroke of the piston, a conduit for feeding a liquid under pressure to said mechanism, and speed responsive mechanism for regulating the pressure of the liquid in the last-mentioned conduit to cause the hydraulic mechanism t'o vary-the effective feed stroke of the piston. 10. A fuel pump system suitable for explosion chambers, comprising a casing bored to provide a. piston cylinder, a fuel feeding piston reciprocable in such cylinder, a fuel feed conduit and a fuel discharge conduit connected with the cylinder space at one end of the piston, a motor piston connected with the fuel feeding piston to operate the latter, said casing being bored toprovide a cylinder for such motor piston, a conduit for delivering a liquid under pressure for operating the motor piston, a slide valve housed within said casing and movable to regulate the feed of such pressure liquid to the motor piston, a conduit for supplying a liquid under pressure for operating the slide valve, timing mechanism connected with the last mentioned conduit for timing the operation of the slide valve, and hydraulically operated mechanism likewise housed within said casing for determining the eective fuel feeding stroke of the fuel feeding piston. A

11.' A fuel pump system suitable for explosion chambers, comprising a casing bored to provide a piston cylinder, a fuel feeding piston reciprocable in such cylinder, a fuel feed conduit and a fuel discharge conduit connected with the cylinder space at one end of the piston, a motor piston connected with the fuel feeding piston to operate the latter, said casing being bored to provide a cylinder for such motor piston, a conduit for delivering a liquid under pressure for operating the motor piston, a slide valve housed within said casing and movable to regulate the feed of such pressure liquid to the motor piston, a conduit for supplying a liquid under pressure for operating the slide valve, timing mechanism connected with the last mentioned Aconduit for timing the operation of the slide valve, a valve for by-passing a portion of the fuel sucked into the firstmentioned cylinder, a member movable with the fuel feeding piston for opening the by-pass valve, and mechanism for determining the position of such member with respect to the by-pass valve atthe beginning of the feed stroke of the fuel feeding piston, comprising a piston connected to said member, a spring acting on one side of the piston urging it in one direction, a conduit for feeding liquid under pressure to the other side of the piston, and means for regulating the pressure in said last-mentioned conduit.

12. A fuel pump system suitable for explosion chambers and comprising a cylinder, a fuel feeding piston reciprocable therein, a fuel feed conduit and a fuel discharge conduit connected with the cylinder space, means for operating the piston, and mechanism for determining the quantity of fuel charged by the piston into the fuel discharge conduit, saidmechanism including a device associated with the piston and adjustable to determine the length of the fuel feeding stroke of the piston, a source of pressure liquid, a member controlled by saidliquid and operative to adthe cylinder space, means for operating the piston, and mechanism for determ ning the eective feed stroke of the fuel feedi g piston, comprising a device associated with the piston and movable to determine the length of the fuel feeding` stroke of the piston, an auxiliary cylinder and piston for operating said device, a source of control liquid of substantiallyl constant pressure connected with the auxiliary cylinder for moving said piston in one orthe other direction, a control member for said operating oil associated with said auxiliary piston, and a source of variable liquid pressure connected with said control member to determine the position thereof and thereby regulating the flow of the constant pressure liquid to one or the other side of the auxiliary piston.

14. A fuel pump system suitable for explosion chambers and comprising a cylinder, a fuel feeding piston reciprocable therein and having a fixed stroke, a fuel feed conduit and a fuel discharge conduit connected with the cylinder space, means for operating the piston, a by-pass valve associated with the cylinder space and hydraulically controlled mechanism for determining the instant of opening of the by-pass valve to thereby determine the amount of fuel fed by the fuel feeding piston during each stroke, said mechanism com'- prising an auxiliary piston and cylinder arranged to cause actuation of said valve, a source of operating liquid of substantially constant pressure for moving said auxiliary piston in one or the other direction, a control device for regulating the flow of said operating liquid to one or the other side of said auxiliary piston, and means for effecting movement of said control device to alter the position of said auxiliary piston and thereby altering the instant of opening of the by-pass valve during the feed stroke of the fuel feeding piston.

15. A fuel pump system suitable for explosion chambers, comprising a cylinder, a piston reciprocable therein, a fuel feed conduit and a fuel discharge conduit connected with the cylinder space, means for operating the piston, an adjustable device for determining the amount of vfuel fed by the piston during each stroke, an auxiliary piston and cylinder for adjusting said device, a conduit for charging operating liquid at substantially constant pressure to said auxiliary cylinder to eect movement of the auxiliary piston in one or the other direction, hydraulic mechanism adapted and arranged to be operated by a separate body of .control liquid of relatively low pressure for controlling the vflow of said `operating liquid, and means for charging such control liquid to said mechanism.

16. A fuel pump system suitable for explosion chambers comprising a cylinder, a piston reciprocable therein, a fuel feed conduit and a fuel discharge conduit connected with the cylinder space at one end of the piston, a motor cylinder and piston for operating said first piston, means for charging operating oil under relatively high pressure to said motor piston to move the same, hydraulic mechanism adapted and arranged to be operated by a. separate body of control oil of relatively low pressure for controlling the flow of said operating oil, means for chargingsuch control oil to said mechanism, and mechanism for determining the quantity of fuel fed by said firstmentioned piston during each pump cycle comprising a by-pass valve, a member connected with the fuel feeding piston for operating said valve, an auxiliary piston and cylinder associated with said member and capable of adjusting the position thereof with respect to the by-pass valve to vary the instant of opening of such valve in rela=l tion to the feeding stroke of the fuel piston. a conduit for delivering said operating oil to said auxiliary piston to eect movement of the latter in one or the other direction, a memberv associated withl said auxiliary piston for controlling the iiow of said operating oil, said member hav ing ports for admitting operating oil to one side of said auxiliary piston and simultaneously discharging oil from the opposite side of said piston, said ports being so disposed' and arranged that said auxiliary piston follows the movements of the control member, a spring for urging said control member in one direction, a conduit for delivering control oil under pressure to said member to act thereon in opposition to said spring, and means for varying the pressureoi said control oil in correspondence with a variable magnitude according to which the supplyof fuel is to be regulated.

i7. A fuel pump system suitable for explosion v chambers, comprising a cylinder. a fuel feeding piston reciprocable therein, a fuel feed conduit and a fuel discharge conduit connected with the cylinderl space at one 'end of the piston, means for operating the piston, and mechanism for regulating the quantity of fuel fed by the piston during its feeding stroke, including an adjustable member adapted to determine the length of the fuel feeding movement of the piston, a hydraulically operated device for adjusting said member, a conduit forA charging a control liquid under pressure to said mechanism, and means for varying the pressure in said last-mentioned conduit.

WALTER. GUSTAV NOACK. 

